Optical head device, inclination detection apparatus using the same, and optical information processing apparatus using the same

1. An inclination detection apparatus, comprising: an optical system for collecting a beam emitted by a light source onto an information memory medium; a light detector for generating a detection signal in accordance with a light amount of the beam reflected by the information memory medium, the light detector including a first light receiving section and a second light receiving section; and a signal processing section for processing the detection signal, wherein: the information memory medium has a first pattern area and a second pattern area, the first pattern area including tracks having a mark and space array, the tracks being arranged adjacently to each other, the mark and space array having a mark and a space, the second pattern area including groove tracks having grooves, the groove tracks being arranged with a prescribed gap therebetween, the mark and space array in the first pattern area includes a first mark and space array and a second mark and space array, which are arranged to be away from a center of the groove tracks by a prescribed distance in a direction substantially perpendicular to the longitudinal direction of the tracks, the first pattern area and the second pattern area are alternately arranged on the information memory medium in a longitudinal direction of the tracks, the detection signal includes a first detection signal and a second detection signal, the first detection signal includes a first light receiving section signal, a second light receiving section signal, a third light receiving section signal, and a fourth light receiving section signal, the first light receiving section signal is obtained from the first light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the second light receiving section signal is obtained from the second light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the third light receiving section signal is obtained from the first light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the fourth light receiving section signal is obtained from the second light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the second detection signal includes a fifth light receiving section signal and a sixth light receiving section signal, the fifth light receiving section signal is obtained from the first light receiving section when the second pattern area is irradiated by the beam collected by the optical system, the sixth light receiving section signal is obtained from the second light receiving section when the second pattern area is irradiated by the beam collected by the optical system, the signal processing section generates an inclination detection signal based on a difference between a first sum signal and a second sum signal, the first sum signal being based on a sum of the first light receiving section signal and the second light receiving section signal, the second sum signal being based on a sum of the third light receiving section signal and the fourth light receiving section signal, and the signal processing section generates a tracking error signal based on a difference between the fifth light receiving section signal and the sixth light receiving section signal.

2. An inclination detection apparatus according to claim 1, wherein: the difference between the first sum signal and the second sum signal is a difference in AC amplitude.

3. An inclination detection apparatus according to claim 1, wherein: the difference between the first sum signal and the second sum signal is a difference in DC amplitude.

4. An optical information processing apparatus, comprising: an inclination detection apparatus according to claim 1; and a correction section for correcting wave front aberration on the beam collected by the optical system, the wave front aberration being generated by an offset of an angle made by the beam collected by the optical system and the information memory medium from a prescribed angle.

5. A method for processing optical information using an inclination detection apparatus including an optical system, a light detector and a signal processing section, the light detector including a first light receiving section and a second light receiving section, the method comprising the steps of: (a) collecting a beam emitted by a light source onto an information memory medium, using the optical system; (b) generating a detection signal in accordance with a light amount of the beam reflected by the information memory medium, using the light detector; and (c) processing the detection signal, using the signal processing section, wherein: the information memory medium has a first pattern area and a second pattern area, the first pattern area including tracks having a mark and space array, the tracks being arranged adjacently to each other, the mark and space array having a mark and a space, the second pattern area including groove tracks having grooves, the groove tracks being arranged with a prescribed gap therebetween, the mark and space array in the first pattern area includes a first mark and space array and a second mark and space array, which are arranged to be away from a center of the groove tracks by a prescribed distance in a direction substantially perpendicular to the longitudinal direction of the tracks, the first pattern area and the second pattern area are alternately arranged on the information memory medium in a longitudinal direction of the tracks, the detection signal includes a first detection signal and a section detection signal the first detection signal includes a first light receiving section signal, a second light receiving section signal, a third light receiving section signal, and a fourth light receiving section signal, the first light receiving section signal is obtained from the first light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the second light receiving section signal is obtained from the second light receiving section when the first mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the third light receiving section signal is obtained from the first light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the fourth light receiving section signal is obtained from the second light receiving section when the second mark and space array in the first pattern area is irradiated by the beam collected by the optical system, the second detection signal includes a fifth light receiving section signal and a sixth light receiving section signal, the fifth light receiving section signal is obtained from the first light receiving section when the second pattern area is irradiated by the beam collected by the optical system, the sixth light receiving section signal is obtained from the second light receiving section when the second pattern area is irradiated by the beam collected by the optical system, and the step (c) includes the steps of: generating an inclination detection signal based on a difference between a first sum signal and a second sum signal, the first sum signal being based on a sum of the first light receiving section signal and the second light receiving section signal, the second sum signal being based on a sum of the third light receiving section signal and the fourth light receiving section signal; and generating a tracking error signal based on a difference between the fifth light receiving section signal and the sixth light receiving section signal.